PollutionCh. 12, section 2

Pg368-376

Learning Objectives

• Describe types of air pollution• Identify causes of water pollution• Explain methods that can be used to prevent

erosion

• Air, water, and soil pollution have many causes, including hazardous waste and the burning of fossil fuels.

New Vocabulary

• Pollutant• Acid precipitation• Runoff• Greenhouse effect• Ozone depletion• Erosion• Hazardous Waste

Keeping the Environment Healthy

• Over 6 billion people live on Earth• Large population puts a strain on the

environment• You can help to lessen the strain by becoming

aware of how you use natural resources

Types of Pollution

• In this section, we will be discussing 3 types of pollution:

1. Air Pollution2. Water Pollution3. Soil Pollution

Air Pollution

• A pollutant is a substance that contaminates the environment

• Pollutants cause hazes over large cities (smog)• Results from burning wood or fuels• Pollutants in the air include soot, smoke, ash,

carbon dioxide, carbon monoxide, nitrogen oxide, and sulfur oxide

• Air pollution can be caused by volcanic eruptions, dust, sand, forest fires, etc…

Acid Precipitation

• Water vapor condenses on dust particles in the air to form droplets that combine to create clouds; when the droplets become large enough they fall as precipitation

• Pollutants from burning fossil fuels can react with water in the atmosphere to form acid rain

Effects of Acid Rain

• Acid rain washes nutrients from the soil• Leads to the death of plants and trees• Runoff from acid rain can run into lakes or

ponds and destroy ecosystems– Lowers pH and kills fish andother organisms

Preventing Acid Rain

• Using low sulfur fuels, such as natural gas or low-sulfur coal can reduce acid precipitation– These are less plentiful and more costly to use

• Smokestacks that remove sulfur dioxide before it enters the air are also effective

• Reducing automobile use and keeping cars properly tuned can help, too

• Using hybrid or electric cars

Greenhouse Effect

• When sunlight travels through the atmosphere some of it is reflected back to the sun but the rest is trapped by atmospheric gasses

• Heat trapping feature of atmosphere is the greenhouse effect.

• Without it temperatures on Earth could possibly be too cold to support life

• Atmospheric gases that trap heat are called greenhouse gases

• One of the most important is CO2• The amount of CO2 is increasing and possibly trapping

more heat = global warming

Greenhouse Effect

• What are the events that cause the green house effect?1. Fossil fuels are burned2. Level of CO2 in the atmosphere increases3. More heat is trapped4. Average temperatures rise

Global Warming

• Data collected from 1895-1995 indicated an increase of 1°C during that period

• No one is certain why or what the results may be (may be human or natural part of Earth)

• Changes caused by global warming:– Changing rainfall patterns– Storms and hurricanes increase– Polar ice caps melt resulting in flooding– Tropical diseases increase (malaria)

Ozone Depletion

• Ozone is about 20km above Earth’s surface• Ozone is a form of oxygen • Absorbs some UV radiation from the sun• Temporarily becomes thinner over each polar

region during its spring season (ozone depletion)

• Thinning is caused by certain pollutant gases called chlorofluorocarbons (CFCs)– Used in cooling systems, refrigerators, freezers

What causes Ozone Depletion?

1. CFC’s are used in cooling systems2. CFCs leak into the atmosphere3. CFCs slowly rise to the ozone layer4. The chemicals react with the ozone (chemical

reaction)5. Ozone molecules break apart

UV Radiation & The Ozone

• Because of ozone depletion the amount of UV rays that reaches Earth’s surface could be increasing

• Causing a rise in the cases of skin cancer & harming other organisms

• Ozone is very important (companies have decided to stop making/using CFCs)

• Ozone is high in the atmosphere & protects life on Earth

• If ozone gets near Earth’s surface it can be harmful– Produced when fossil fuels are burned– Pollutes air in lower atmosphere – Damages lungs & sensitive tissues of animals & plants

Indoor Air Pollution

• Air pollution can occur indoors as well as outdoors• Today’s buildings are much more energy efficient

(better insulation, etc…) but they may also trap harmful substances in rooms by lessening air flow

• For example, paints, adhesives, carpets, glues, printers, & photocopy machines give off dangerous gases (formaldehyde)

• These gases are carcinogens (can cause cancer)

Carbon Monoxide

• Another type of air pollutant• Poisonous gas released when charcoal, natural

gas, kerosene, or other fuels are burned• CO poisoning can cause severe illness or death• It is colorless and odorless making it difficult to

detect• Alarms are used to detect the presence of CO

Radon

• Naturally occurring radioactive gas• Given off by some types of rock & soil• Has no color and no odor• Seeps into basements and lower floors of

buildings• Second leading cause of lung cancer in the U.S.• Radon detectors can alert of increasing levels of

gas

Water Pollution

• Pollutants can enter water by drifting or falling in rain

• Rain can also wash land pollutants into waterways• Factories and sewage treatment plants release water

into waterways• Laws require that wastewater be treated to remove

pollutants before it is released• Water pollution can also occur when people dump

litter or waste into rivers, lakes, oceans, etc…

Surface Water

• Some water pollutants poison fish and other wildlife and can be harmful to people who may swim or drink the water

• Chemical pesticides sprayed on farmland can wash into lakes and streams

• Chemicals can harm the animals that fish, turtles, or frogs rely on for food

• Shortages of food lead to death among water-dwelling animals• Mercury and other metals can build up in tissues of fish & be

transferred to people• Algal blooms can be another pollution problem

– Fertilizer contains large amounts of nitrogen– Can cause rapid growth of algae– Algae die and are decomposed by bacteria that use of oxygen

Ocean Water• Polluted water can enter oceans • Oil spills can also cause water

pollution• About 4 billion kg of oil is spilled into

the ocean every year

• “All streams lead to the ocean.” – Finding Nemo

Groundwater

• Pollution can affect water that seeps underground• Groundwater is water that collects between

particles of soil and rock• Comes from precipitation and runoff that soaks

into soil• Flows slowly through permeable layers of rock

called aquifers• Polluted groundwater is difficult and sometimes

impossible to clean

Soil Loss

• The movement of soil from one place to another is called erosion.

• Eroded soil that washes into a river or stream can block sunlight and slow photosynthesis

• It can also harm fish, clams, and other organisms

• Erosion is a natural process but humans can increase it

Soil Pollution

• Not only does pollution affect air and water, soil may also become polluted.

• Soil can be polluted when air pollutants drift to the ground or when water carries pollutants as it flows through soil

• Tossing litter on the ground or disposing of trash in landfills may cause soil pollution, also

Solid Wastes

• Most solid waste is dumped in landfills• Most landfills are designed to seal out air and

water to prevent pollutants from seeping into the ground

• This slows down the normal decaying process though– Paper and food do not decompose as quickly and

build up year after year

Hazardous Wastes

• Waste materials that are harmful to animals or humans or any living organisms are called hazardous wastes.

• Include chemicals such as pesticides, oil, and petroleum-based solvents, radioactive materials used to treat disease, and nuclear weapons

• Usually hazardous wastes are disposed of separately from regular trash to be treated in ways to prevent environmental production

What have you learned?

• List 4 ways that air pollution can affect the environment.

• Explain how an algal bloom can affect other pond organisms.

• Describe possible causes and effects of ozone depletion.

• How could hazardous wastes in landfills eventually affect groundwater?